Refrigerating systems, such as air conditioners, usually comprise two blade assemblies which after being incorporated to a respective tubular central hub are mounted to an ordinary drive motor. Such mounting is usually made by tight fitting the tubular central hub to an adjacent shaft end of the motor.
In a known prior art form to mount said central hub to the motor shaft, the central hub-shaft end assembly, after being mounted, receives a fixing element that will act on both engaged pieces, avoiding relative longitudinal movements therebetween. The relative rotational movement is avoided by the semi-circular shape of both the shaft end and tubular central hub.
In a known form for mounting the fan to the motor shaft (FIG. 1), the retention between said pieces is obtained by providing a metallic band surrounding the tubular central hub after the latter has been mounted to the corresponding motor shaft end. In this construction, the fixation occurs by compressing the tubular central hub against the shaft end.
In another known construction, (FIG. 2), the fan-motor shaft assembly is made by the introduction, into a radial throughbore provided in the tubular central hub, of a screw that acts against the adjacent surface of the motor shaft, restraining the latter from the relative longitudinal movement mentioned above.
Although these constructions allow an adequate fixation of the fan to the motor shaft, said solutions present some disadvantages, such as the need for additional parts and a difficult slow mounting operation that will consequently increase the cost of the product.